1. Field of the Invention
The present invention relates to a lubricating coating compound for a sliding member, a sliding structure combining two sliding members respectively having sliding surfaces held in sliding contact with each other, wherein the lubricating coating compound is applied to at least one of the sliding surfaces, and a slide bearing apparatus using the sliding structure.
2. Description of the Related Art
As lubricating coating compounds, various types are known including (i) one in which an oil-based composition is applied by spraying or the like and is used in a wet state, (ii) one in which after a coating is formed, a solvent is allowed to volatilize, and the coating is used as a dry film, and (iii) one in which a coating is allowed to cure under the normal temperature or on heating and is used as a cured film.
The lubricating coating compounds (i) and (ii) are used in the form of one kind of lubrication in which a lubricating composition is supplied to opposing surfaces of two members which slide with respect to each other on their opposing surfaces.
Namely, the lubricating film formed by each of these lubricating coating compounds (i) and (ii) is not formed in the two sliding members themselves, but is, in a word, interposed between their opposing surfaces. Accordingly, when such a lubricating film has been consumed, the lubricating film can be formed again by performing similar spraying or the like.
In contrast, the lubricating coating compound (iii) is different in kind from the lubricating coating compounds (i) and (ii). Namely, the lubricating coating compound (iii) forms a portion or portions of either one or both of the two sliding members, i.e., a surface layer of the sliding member is formed.
It is desired that this surface layer, i.e., the film which forms the sliding surface, excel in the mechanical strength, have good adhesion to a substrate, should not be damaged by an external force or worn out easily during sliding, or should not exfoliate from the substrate.
Here, the imparting of lubricity to the film, on the one hand, and the mechanical strength of the film and its adhesion to the substrate, on the other hand, are in an apparently incompatible relationship, and there is a problem in that if an attempt is made to improve the lubricity, the strength and adhesion inevitably decline.
In addition, in a combination of two sliding members held in sliding contact with each other, in a case where one sliding member, particularly its sliding surface, is formed of a synthetic resin, a metallic sliding member, such as one formed of steel, is generally used as the mating member. However, there are cases where the mating member itself is also formed of a synthetic resin or at least its sliding surface is formed of a synthetic resin in view of various purposes and needs, i.e., for the purposes of rust prevention, chemical resistance, electrical insulation, light weight, and a requirement in design.
As such an example, it is possible to cite, among others, a combination of a synthetic resin bearing and a steel-made shaft provided with a synthetic resin coating, a combination of gears each formed of a synthetic resin, and a control cable made up of a combination of a synthetic resin pipe and a wire rope which is coated with a synthetic resin, is inserted therein, and is adapted to be pushed and pulled (undergo reciprocating sliding) or undergo rotational sliding.
However, in the case of the combination of the sliding members formed of a synthetic resin, even in the case of a tetrafluoroethylene resin which is known to have a low coefficient of friction, it is difficult to lower the coefficient of kinetic friction to 0.1 or less in sliding under a dry frictional condition.
On the other hand, in a slide bearing apparatus having the function of allowing the displacement of a structure to escape through sliding in response to earthquake motion, if the coefficient of friction acting on its sliding surface is large, sliding displacement fails to be performed desirably, and effective vibration isolation fails to be demonstrated, so that it is desired that the frictional resistance at its sliding surface should be low.
Furthermore, with the slide bearing apparatus, since the apparatus does not operate other than when a force is applied thereto due to an earthquake or the like, in order to obtain a stable vibration isolation effect, it is required that the frictional resistance during operation should be stable, i.e., the change over time of the coefficient of static friction should be small. Namely, it is required that, in addition to the fact that the coefficient of kinetic friction should be low, the coefficient of static friction should also be low and stable.
However, in the case of the combination of sliding members formed of a synthetic resin, the coefficient of static friction generally shows a value which is not less than two times the coefficient of kinetic friction. Furthermore, in cases where the apparatus is under load and is normally not operated, the coefficient of static friction tends to become gradually large due to microscopic creep ascribable to the contact of the two members over a long period of time.
Accordingly, although both the coefficient of static friction and the coefficient of kinetic friction can be lowered by applying a lubricant such as grease or oil to the sliding surfaces, the lubricant comes to be discharged from the sliding surfaces over short periods of time, and its effect is lost. Moreover, the coefficient of friction gradually rises due partly to the effect of the solidification or deterioration of the lubricant over time.
The present invention has been devised upon finding that it is extremely effective to compound with an epoxy resin, i.e., a base resin, a reactive silicone oil which cures by forming a three-dimensional network structure in the presence of a crosslinking agent, a triazinethiol which is a crosslinking agent for this reactive silicone oil and has the function of modifying the substrate surface as a surface suitable for bonding, and, as necessary, a nonreactive silicone oil in addition to them.
Accordingly, it is an object of the present invention to provide a lubricating coating compound which is used for forming a thermosetting synthetic resin lubricating film, forms its surface layer integrally with a substrate, and exhibits an excellent low-friction characteristic, thereby overcoming the above-described drawbacks of the conventional art.
Another object of the present invention is to provide a sliding structure combining two sliding members which exhibits a coefficient of static friction and a coefficient of kinetic friction that are stable and low, and which causes low-friction sliding to take place reliably and effectively when sliding is required, as well as a slide bearing apparatus using the sliding structure.
In accordance with a first aspect of the present invention, there is provided a lubricating coating compound used for forming a thermosetting synthetic resin lubricating film, wherein 100 parts by weight of an epoxy resin, 2 to 30 parts by weight of a reactive silicone oil with an epoxy group, and at least W part by weight of a triazinethiol calculated by the following relation are dissolved in an organic solvent:   W  =                                                        (                              amount                ⁢                                  xe2x80x83                                ⁢                of                                                                                        epoxy              ⁢                              xe2x80x83                            ⁢              resin                                                                                          used                ⁢                                  xe2x80x83                                ⁢                100                            )                                          xc3x97              S                  E          1                      +                                                      [                              amount                ⁢                                  xe2x80x83                                ⁢                of                ⁢                                  xe2x80x83                                ⁢                reactive                ⁢                                  xe2x80x83                                ⁢                silicone                                                                                        oil              ⁢                              xe2x80x83                            ⁢              with              ⁢                              xe2x80x83                            ⁢              an              ⁢                              xe2x80x83                            ⁢              epoxy              ⁢                              xe2x80x83                            ⁢              group                                                                                          used                ⁢                                  xe2x80x83                                ⁢                                  (                                      from                    ⁢                                          xe2x80x83                                        ⁢                    2                    ⁢                                          xe2x80x83                                        ⁢                    to                    ⁢                                          xe2x80x83                                        ⁢                    30                                    )                                            ]                                          xc3x97              S                  E          2                    
where E1 is an epoxy equivalent of the epoxy resin used, E2 is an epoxy equivalent of the reactive silicone oil with an epoxy group used, and S is the number of grams of the triazinethiol containing 1 gram-equivalent of mercapto groups xe2x80x94SH.
Namely, in accordance with the first aspect of the present invention, there is provided a lubricating coating compound used for forming a thermosetting synthetic resin lubricating film, wherein 100 parts by weight of an epoxy resin, 2 to 30 parts by weight of a reactive silicone oil with an epoxy group, and a triazinethiol in an amount sufficient to cause at least crosslinking of the epoxy groups of these two components are dissolved in an organic solvent.
In accordance with another aspect of the present invention, for the purpose of modifying the aforementioned synthetic resin lubricating film, there is provided the lubricating coating compound used for forming a thermosetting synthetic resin lubricating film, wherein at least one of 2 to 30 parts by weight, preferably 2 to 15 parts by weight of at least one of inorganic and organic filler powders and 0.5 to 5 parts by weight of at least one of oil and a wax-like substance is further dissolved or dispersed in the organic solvent.
Further, there is provided the lubricating coating compound used for forming a thermosetting synthetic resin lubricating film, wherein, of the aforementioned components of the composition, part of the triazinethiol is replaced by curing agent such as a polyamine, an acid anhydride, a phenolic resin, a polyamide resin, or a mercaptan-based compound.
Furthermore, in the lubricating coating compound used for forming a thermosetting synthetic resin lubricating film in which the resin composition composed of an epoxy resin, a curing agent, a reactive silicone oil with an epoxy group, and a triazinethiol are dissolved in an organic solvent, if a sum of the epoxy resin component and the curing agent component is set to 100 parts by weight, a sum of the reactive silicone oil with an epoxy group and the triazinethiol is from 2 to 30 parts by weight, preferably 2 to 15 parts by weight. Here, if the sum of the epoxy resin and the curing agent is set to 100 parts by weight, 2 to 10 parts by weight of a nonreactive silicone oil is preferably compounded in the composition.
In addition, in accordance with another aspect of the present invention, there is provided a sliding structure combining two sliding members including a first sliding member and a second sliding member which are held in into sliding contact with each other on sliding surfaces thereof, wherein the sliding surface of the first sliding member is formed of a lubricating film made of a thermosetting synthetic resin, and the sliding surface of the second sliding member is formed of a synthetic resin, the lubricating film being a film of a composition composed of an epoxy resin, a reactive silicone oil with an epoxy group, and a triazinethiol.
In accordance with still another aspect of the present invention, there is provided a slide bearing apparatus comprising the aforementioned sliding structure which causes sliding to take place during an earthquake so as to exhibit a vibration isolating action.
In accordance with the present invention, it is possible to provide a lubricating coating compound for forming a synthetic resin film, in which its surface layer is formed integrally with the substrate, and which exhibits an excellent sliding characteristic.
In addition, in accordance with the present invention, it is possible to provide a sliding structure combining two sliding members which exhibits a coefficient of static friction and a coefficient of kinetic friction that are stable and low, and which causes low-friction sliding to take place reliably and effectively when sliding is required, as well as a slide bearing apparatus using the sliding structure.
Hereafter, a description will be given of embodiments and examples of the present invention. It should be noted that the present invention is not limited to these embodiments and examples.